Howdy guys I'm the new guy on the block. Just bought a 94 coupe LT1 with a 6 speed. Showing 86+ K. I should be smilin but in the last week its taken the smile right off my face. So I'm here to ask for a bit of help.

I'm not a stranger to a wrench nor am I entirely new to electronics. But I'm old enought that the bulk of my electronics training goes back to analog stuff. My idea of a high performance car is a 69 Fairlane 351 and computers sit in the office not on the firewall of a car. However I am an adaptable sob and I'm gonna try my hand at this. I'm gonna see if you guys can help me fix this thing. I never have and still don't have a heckuva lot of faith in repair shops around these parts. So my shot is probably as good as theirs at least for a start.

A little background first. Car seems to be in great shape. As near as I can tell it was owned by 2 older guys prior to me and is stock except that a module has been added that allows one to shift thru all gears all the time. No 1-4 stuff. Recently tuned and passed emmisions in MD the day before I bought it.

So here I am dumb fat and happy tooling along last Saturday and it coughs...Kinda like a slug of water running thru it. I figure well...It will be ok but I better keep an eye on it. Later that day I'm cruising the interstate enjoying the ride at about 75 mph and BAM it just quits...Nothing... No check engine light...all gages working...just see ya! I roll to the shoulder shut down the a/c and crank her...No start ...wait 2 minutes try again...Vroom! away we go but the CHECK ASR light is on. I head for the shack and make it. No further problem. Go do what I need to do and come back and crank her up. CHECK ASR light gone...No problems! Needless to say I am not a trusting sole so no hightway stuff now until I figure this out. Works fine all week ...No further problems...Then today...cruising along...Cough... sputter ...CHECK ASR...cough ...sputter ..quit...Crank ..VROOM ... And this pattern repeats intermittently until I drag out tired @$$ home and I park it.CHECK ASR showing each time until I crank it back up. Only pattern to it is that both last Saturday and today were hot. Outside temp in the 90's and I had the air on. But this time even with the a/c off she took a $#!+ on me once. Any ideas?

Twinamp

 

first thing you need to do is see if you have set any error codes:
http://www.georgiasyty.com/aldl.htm

here's another link specific to GM :
http://www.troublecodes.net/GM/

can you turn off your ASR, and see if the problem still persists? As a matter of habit, I always turned off my ASR right after starting the engine....
Clearly this is a dangerous problem and needs to get fixed ASAP....

 

Sounds like a bad ICM or opti. Hopefuly, the codes will point you in the right direction.

-Mike

 

Thanks guys. When I located the DTP it appears to have no "B" terminal. According to one source that is a possibility. In another thread

http://forums.corvetteforum.com/show...4+engine+codes

Casethecorvetteman posted a process to retrieve codes on a 94 but only identified the pins by number He said to jumper pins "12" and "4".

Are they different from the "A" and "B" ?

Thanks!

Twinamp

 

What part of the country are you located? I have a laptop computer all setup for tuning and dataloging on that computer.

 

yes, case is correct if you have a 16 pin ALDL, then short pin4 and 12.

 

Be aware, also, that the codes do NOT identify the failed component. They merely point to the sensor that sent, the out of parameter info, that triggered to light and the code. Now, one has to trouble shoot to find the cause of the fault. The FSM has trouble shooting charts to follow to track down the cause of most of the codes. You are pretty much flying blind, without one.

RACE ON!!!

 

Welcome to the site

 

"My idea of a high performance car is a 69 Fairlane 351 and computers sit in the office not on the firewall of a car."

heh heh..didn't you mean a '69 Camaro SS 350 ??

 

Thanks to all the folks that have posted.

Sorry I've been away so long. But first things first. Had a 7 year olds championship baseball game to attend. (We won! ) And then we've had thunderstorms so no confuser ...err...computer. With all the goings on I haven't had time to look at the 'vette. I very much appreciate all the help. I understand that the codes won't directly point to the problem but at this stage of the game, with the problem being intermittent anything will help!

As to my location. I'm in MD just outside of DC. We are suffering from a tupical bout of DC summer weather. About 90 degerees 163% relative humidity and thunder storms about every 2 hours. I'm going to take a look at the connector I believe its the 95 style mentioned in one of the posts. More later after I can get to it.

Twinamp

 

The code that shows up just means the PCM saw a voltage or signal outside it's parameter. Whatever code shows up is where you start looking for the problem. Either sensor/item, connection, or wiring.

 

Don't wash your engine bay,the opti will take a $hit.

 

Amazing what a few minutes of dry weather and a properly positioned paper clip will do to enlighten one.....

Codes: C21 (Which according to Case is a good thing.)

Then in module 9:

H21
H25
H62

All other modules show:

----


I open to any and all suggestions.

Twinamp

 

see if you can locate you error code descriptions here:
http://www.troublecodes.net/GM/

then report back......

BTW...no telling how long those codes have been stored...you can clear them by disconnecting neg. battery post for 30 seconds. Reconnect, then drive a few days and recheck error codes. Also that first code s/b a C12 not C21.....This is just indication of start of error code dump

 

I would reset the codes as described above. Then see if the same ones show back up. The H stands for history and could have been they awhile back. The C stands for current.

21
TPS voltage was above 2.5 volts for 3 seconds when the engine was running, or when the TPS was above 4.8 volts at any time.

25
Inlet air temperature sensor signal showed an air temperature over 302° F for 12 seconds after the engine has been running for 4 minutes.

62
Engine oil temperature sensor indicated an oil temperature above 284° F after engine had been running for 30 minutes.

If they don't clear, the next item to purchase is a 94 FSM. Best tool to have.

 

Welcome and good luck!

 

It would be easier to go to AutoZone or similiar parts store that will bring out a codereader and read your codes for FREE......probably even tell you what they mean.....

 

hm... whenever the ASR acts up, and the engine sputters, I would have to blame something to do with the tach feed.... which leads me to the Ignition Control Module.

Now, I am not indicting the ICM, what I am suggesting is you check it, AND, the harness that attaches it. Jet-Jock had a problem with his 93, that was caused by the harness not making good contact.

 

Thanks for the help guys. When the monsoons break I'm gonna go have a look around. The loose wire/ connector thing has a right sorta feel about it due to the way it is intermittent. Also I'm gonna let it idle and warm up and just tap on the control module to see if something is loosy goosy in there. Next I'll probably clear the codes and see if they reset.

I'll keep you'll posted on the progress. I really appreciate all the help. Anybody else got any ideas?

(What do you have when you a blind deer?....I have No eye deer!..har har puke!)

Later!

Twinamp

 

H21... that is another piece of info that the ASR needs to function.